A diamond and emerald necklace featuring the 163.41-carat gem was sold to an anonymous bidder at a Christie’s auction in Geneva.

A necklace featuring a 163.41-carat flawless white diamond was sold for a record $33.7 million at a Christie’s auction in Geneva on Tuesday (November 14).

The diamond, which is the largest of its color and clarity ever presented at auction, was sold to an anonymous telephone bidder. The gem was cut from a rough 404-carat stone found in Angola last year.

Designed and manufactured by Swiss-based jeweler de Grisogono, the necklace is framed by 18 emerald-cut diamonds, with pear-shaped emeralds adorning the sides. According to Christie’s, it took more than 1,700 hours to create.

“It’s 50 carats larger than the last one of its kind,” said Rahul Kadakia, international head of jewelry at Christie’s. “It’s completely flawless.”

The prior record for the most expensive colorless diamond to sell at auction was an oval-cut diamond of 118.28 carats sold in Hong Kong by rival Sotheby’s (NYSE:BID) for $30.6 million in 2013.

Despite the record-setting sale, Tobias Kormind, managing director of 77Diamonds.com, Europe’s largest online diamond jeweler, believes the price of “The Art of de GRISOGONO” fails to reflect the fact that it has more carats than the previous record holder.

“This is a worrying sign for the top end of the diamond market suggesting it is not as immune as one would have hoped to downward price pressures caused by global factors such as the Chinese slowdown, Russian sanctions and lower oil prices,” he said in a statement.

Total proceeds from the Christie’s auction came to $106.1 million. That brings the total for the company’s Geneva auctions in 2017 to $258,588,868, with 27 lots sold for over $1 million.

The fall auction season in the Swiss city ended on Wednesday (November 15), after Sotheby’s failed to sell the rare “Raj Pink” diamond. “Pieces must be exceptional to sell today at the same level as two years ago,” Eric Valdieu, a Geneva-based jewelry dealer formerly of Christie‘s, told Reuters after the auction.

Sotheby’s holds the record for the most expensive diamond ever auctioned, having sold the 59.6-carat “Pink Star” for $71 million to Hong Kong-based jewelry retailer Chow Tai Fook.